Question

Which would have the greatest influence on the alkalinity of the whole ocean and why? a) Increase in the weathering of carbonate rocks on land b) Decrease in fossil fuel emissions of CO2 or c) Increase in the standing stock of phytoplankton in the surface ocean

Answer 1

The greatest influence on the alkalinity of whole ocean would be due to, (a) Increase in the weathering of carbonate rocks.

Carboncate from rocks helps maintain any change in the pH due to dissolution of CO2 from the atmosphere into the ocean. The CO2 thus dissolved reacts with water to form H2CO3 which dissoicates to give H+ ions in water thus raising lowering the pH of water. carbonates from rocks now play a major role in reacting with the H+ and reforming H2CO3, thereby any change due to H+ is nullified. Now If large amounts of carbonate are formed from rock, then the alkalinity of ocean would rise due to greater amounts of OH- formed in water, thus influencing alkalinity to the greatest extent.